F-actin-capping protein (CapZ) (CapZ)

F-actin-capping protein, commonly known as CapZ, is a heterodimeric complex consisting of alpha and beta subunits that serves as a fundamental regulator of the actin cytoskeleton (UniProt P52907, P06748). It functions by binding with high affinity to the barbed (fast-growing) ends of actin filaments, effectively capping them to prevent further polymerization or depolymerization (Cooper & Sept, 2008). This activity is crucial for maintaining the length and stability of actin filaments, which is essential for cellular processes such as motility, endocytosis, and the maintenance of cell shape (Hart & Cooper, 1999). In cardiac and skeletal muscle, CapZ is localized to the Z-disks, where it anchors the thin filaments of the sarcomere, playing a vital role in myofibril assembly and contractile force transmission (Lin et al., 2016). Dysregulation or mutations in CapZ subunits have been implicated in various pathologies, including dilated cardiomyopathy and the metastatic spread of cancer cells, where altered actin dynamics facilitate invasion (PubMed 21907141, 25135935). Although CapZ is not yet a target for FDA-approved drugs, it is an active area of research for developing modulators that could stabilize muscle structure or inhibit cancer cell migration.

Other names

CapZCapping protein (actin filament) muscle Z-lineCAPZA1CAPZA2CAPZBBeta-actininF-actin-capping protein complex

Binding to the barbed end of actin filaments to inhibit the addition and loss of actin subunits (capping), thereby regulating filament length and dynamics.